The present invention generally relates to liners for cargo containers, and more specifically, to liners for containers that are used to carry bulk cargo.
Standardized containers or boxes have come into very extensive use for the shipment of freight by land and sea, and the many advantages of such containers have made it extremely desirable to adapt them for use with as many types of cargo as possible. Accordingly, there have been attempts, with varying degrees of success, to use such standardized containers to carry bulk cargo such as dry bulk chemicals, powdered and pelletized resins, flour, coffee beans, and grain.
When cargo containers are used to carry such bulk cargo, it is important that the container itself either be kept clean or be cleaned after each load of cargo is emptied from the container, so that the container can be subsequently used with another load of cargo. Moreover, it is important to protect the bulk cargo from contamination and from undesirable exposure to the natural elements.
For these reasons, large plastic removable liners are often used to line the interior walls or surfaces of cargo containers that are used to carry bulk cargo. The liners protect the cargo during shipment, for example, from rain and debris; and after the cargo is delivered, the liner can be removed so that the container is again useable, without significant cleaning, to carry other cargo.
Various difficulties have been encountered, however, in using plastic liners in the above-described manner; and in particular, it has been found that the liners may tear or rupture under certain conditions. For example, the general practice in the industry is to try to secure the liners comparatively tightly inside the cargo containers so as to minimize movement of the liners therein. However, bulk cargo loads often shift; and if such a load shifts inside a liner that itself is practically immovable inside a cargo container, then the shifting load may produce high localized stresses on the liner, which in turn may cause the liner to tear or rupture.
In addition, with liners that are used in the above-discussed manner, bulkheads are often secured to the back ends of the liners to help hold and support the liners inside cargo containers, particularly when cargo is being loaded into and discharged from the liners. Commonly, a bulkhead is secured to the back end of a liner by mean of an adhesive, by staples or both; and during transportation, a bulkhead may partially break away from a liner, tearing or rupturing the liner.